Rotary abrasive heads



July 26, 1955 J sw 2,713,759

ROTARY ABRASIVE HEADS Filed March 23, 1953 2 Sheets-Sheet l INVENTORATTORNEY y 6 1955 R. .J. SWAN 2,713,759

ROTARY ABRASIVE HEADS Filed March 23, 1955 2 Sheets-Sheet 2 55, H IINVENTOR 4M 9. 4%

BY 14 3. MM

ATTORNEY United States Patent ROTARY ABRASIVE HEADS Richard James Swan,London, England, assignor, by mesne assignments, to Engis EquipmentCompany, Chicago, lih, a corporation of Illinois Application March 23,1953, Serial No. 343,956- Ciairns priority, application Great BritainApril 16, 1952 4 Claims. (Cl. 51--193.7)

The present invention relates to rotary abrasive heads of the kindcomprising, when in use a plurality of brushes detachably mounted insockets extending from a supporting plate in a direction parallel to theaxis of rotation of the head, the sockets together forming asubstantially cylindrical array, and abrasive-strips extending outwardlybetween the brushes, the inner portions of the abrasive strips beinganchored and rolled upon each other within the space defined by thebrush sockets to form a single spool concentric with the axis ofrotation of the head.

An object of the invention is to facilitate the adjustment of such ahead for the purpose of increasing or decreasing the lengths of the freeend portions of the abrasive strips projecting between the brushes.

A further object of the invention is to provide a rotary abrasive headof simplified construction.

A still further object of the invention is to increase the number ofangular positions in which the core can be fixed after adjustment, thusvarying the length of the ends of the abrasive strips projectingoutwardly beyond the circumference Within fine limits.

Yet another object of the invention is toprovide a rotary abrasive headin which the length of the abrasive strips projecting beyond the ends ofthe brushes may be adjusted without removing the clamping device and theend plate.

According to the present invention a rotary abrasive head of the kindreferred to comprises a brush-carrying assembly including a supportingplate adapted for mounting on a driving shaft and a ring of individualbrush holders each of which is fixed at one end to said supportingplate, an abrasive-strip anchorage assembly including a core and aplurality of anchorages for anchoring groups of abrasive-strips, thesaid abrasive-strip anchorage assembly having one of its ends rotatablymounted in said brushcarrying assembly, an end plate keyed on the freeend of said core and having locating means for locating the adjacentends of said brush holders,' a screw-threaded clamping device engaging ascrew-threaded portion on the free end of said core and locking meansengageable and disengageable by axial displacement of said clampingdevice to lock and release respectively said brush-carrying assembly forrotation relative to said abrasive-strip assembly.

The invention will now be described with reference to the accompanyingdrawings in which:

Fig. 1 is an end elevation of an abrasive head with a detachable endplate and clamping screw removed,

Fig. 2 is an axial cross-section of the abrasive head, with certainparts shown in elevation,

Fig. 3 is an end view of an end plate of the abrasive head,

Fig. 4 is a perspective view of a rotatable supporting plate with brushholders and a central core in position but other parts removed for thesake of clarity,

Fig. 5 is an axial cross-section of an alternative construction ofabrasive head, with certain parts shown in elevation, and

Fig. 6 is an elevation of a fragment of the supporting plate of thesecond abrasive head shown in Fig. 5.

In the abrasive head shown in Figs. 1-4, a main supporting plate 1 takesthe form of a circular disk having a flange 2 and a hollow boss 3concentric with the disk 1. The boss 3 serves to accommodate a drivingshaft and has two tapped holes 4 (only one shown) accommodating setscrews. On the opposite side of the supporting plate, a concentric shortcylindrical socket 5 is provided for the reception of a flange 6 on oneend of a cylindrical core member 7. The cylindrical socket is groovedinternally to receive a circlip 8 by means of which the flange 6 of thecore 7 is restrained from axial displacement.

The core member 7 is formed with three uniformly spaced axial bores 9which communicate with the outside of the core member 7 through axialslots 10. The bores 9 and slots 10 extend from the free end of the coremember to points within the core member 7 just short of the end held inthe cylindrical socket 5. Each of these main axial bores 9 is adapted tohouse an anchoring pin 11 and the looped inner end of an assembly ofabrasive-strips, which strips pass out from the core member through thecorresponding slot 10 and pass between peripheral brushes in knownmanner. The portion of the core member 7 at its free end is ofsubstantially hollow cylindrical form. Three end plate locating slots 12are in line with the abrasive-strip guiding slots 10 and are thuslikewise equally spaced about the circumference of the core 7. Thehollow cylindrical portion of the core is formed with an internalscrew-thread.

A removable end plate 13 has a central aperture 14 (Fig. 3) with a hubportion 15 having three splines 16 adapted to engage the locating slots12. The splines 16 on the hub 15 have a length such that a clampingscrew 22 may be slackened, a projection disengaged and the brushassembly rotated with respect to the core assem bly without removing theend plate completely. The end plate 13 is also provided with aperipheral flange 17 similar to that of the supporting plate 1, and aninner flange 18 a short distance from and coaxial with the peripheralflange 17. The flanges 17 and 18 are disposed with their inner and outeredges respectively fitting closely to the free ends of a ring of brushsocket members. Twelve dovetail socket members 19 are equally spacedround the periphery of the supporting plate and are rigidly fixed to theplate by means of screws 20. Brushes 21 are removably fitted in thesocket members 19 and may be firmly held by means of the end plate 13.The free ends of the brush socket members 19 are partly cut-away in 4order to accommodate the flange 18 of the end plate.

The end plate 13 is clamped to the remainder of the abrasive headassembly by means of a clamping screw 22 having a-knurled head. Thisscrew has an annular recess 23 which is adapted to fit over the end ofthe core 7 when screwed down. The peripheral flange 24 outside therecess 23 engages the radially inner portion of the end plate 13 andwhen the clamping screw 22 is screwed down the flange 24 holds the endplate firmly against the ends of the brush socket members.

When it is necessary to adjust the length of abrasive strip 30projecting beyond the ends of the brushes, the clamping nut 22 isslackened and the end plate 13 displaced axially until the projection 25is disengaged. The edge of the end plate 13 which is preferably knurled,is held in one hand and turned with the core assembly with respect tothe supporting plate 1. The outside of the driving boss 3, may also beknurled in order to provide a hand grip. After adjustment has beencompleted the clamping screw 22 is tightened thus causing the projection25 to engage the free end of a fresh brush socket member or a freshspace between two adjacent socket members.

The alternative construction shown in Figs. 5 and 6 differs from oneconstruction according to Figs. 1-4 only as regards the locking meansand similar parts to those in the first described embodiment are denotedby the same reference numerals but with the addition of a suffix.

In Figs. 5 and 6 a ring of six holes 261 are shown in the inside of thesupporting plate 11. Each of these holes 261 is countersunk until itsedges meet the corresponding edges of the countersunk holes on each sideof it. Between two of the main axial bores 91 in the core 71, a smallerbore is provided and accommodates a plunger 271 (shown in broken linesin Fig. 5) formed in two parts 271 and having between the two parts acompression spring 281 which acts in a direction tending to engage theend of the plunger with one of the holes of the abovementioned ring ofholes 261. The end of the plunger 71 remote from the supporting plate isengaged by one end of the clamping screw 221 which co-operates with theinternally screw threaded upper portion of the core 71. The upperportion of the core also has a longitudinal external groove 291 which isadapted to co-operate with a spline formed in the inside of the hub 151of the end plate 131. Thus when the clamping screw 221 is slackened thespring acting in the plunger bore allows the lower end of the plunger271 to be disengaged from its co-operating hole 261 in the supportingplate 131 and the core assembly may be rotated with respect to thesupporting plate assembly. The core assembly may be reclamped when thedesired length of abrasive strip 301 has been wound in or unwound byre-engaging the plunger 271 in another hole 261 and locking it inposition by retightening the clamping screw 221.

In either of the above described embodiments, to remove and replace oneor more of the abrasive strip assemblies, after loosening the clampingscrew 22 or 221 removable end plate 13 or 131 is turned to rotate thecore member 7 or 71 until the abrasive strips 30 or 301 are fullyunwound from the core member 7 or 71. The clamping screw 22 or 221 andthe removable end plate 131 are now completely removed and the requiredabrasive strip assembly with the corresponding anchorage pin 11 or 111or each such assembly and pin, is removed endwise. After a freshassembly has been slipped over the pin, this fresh assembly is replacedendwise together with the pin into the bore and slot in the core member.The removable end plate 131 is next replaced and turned until thedesired proportion of abrasive strip 30 or 301 is wound up on the coremember 7 or 71. Finally the clamping screw 22 or 221 is replaced andscrewed tight to retain the core member 7 or 71 against further relativerotation while at the same time clamping the anchoring pins 11 or 111tight and clamping the end plate 13 or 131 against the sockets for thebrushes and against the backs of the brushes 21 or 211 in said sockets17 or 171.

I claim:

1. A rotary abrasive tool, comprising a main end plate adapted to bedetachably mounted on a driving shaft, a plurality of closely spaceddovetail brush socket elements each secured at one end to said main endplate adjacent the circumference thereof and extending parallel to therotary axis of said main end plate, said socket members together forminga substantially cylindrical array, a plurality of closely spacedoutwardly extending brushes detachably mounted respectively in saidsocket members, a spool attached at one end to said main end plate forrelative rotation with respect thereto about said rotary axis, aplurality of abrasive strips wound upon each other on said spool withthe free ends thereof extending outwardly between adjacent brushes, anadjustable end plate keyed for sliding movement on the other end of saidspool and provided near its circumference with at least one projectionadapted for selective engagement with the free ends of said brush socketmembers, and a screw-threaded clamping member having a shank screwconnected to the other end of said spool and a head engageable with theside of said adjustable end plate remote from said main end plate, saidclamping member being adjustable between a clamping position in whichthe adjustable end plate and spool are locked by the projection againstrotation relatively to the main end plate and brush socket members and areleased position in which the adjustable end plate is axially movableto a position to disengage said projection and thereby permit suchrelative rotation.

2. A rotary abrasive tool as claimed in claim 1, wherein said projectionis selectively engageable in the free ends of individual brush socketmembers as well as between the free ends of adjacent socket members.

3. A rotary abrasive tool as claimed in claim 2, wherein the free endsof the brush socket members are cut away and the adjustable end plate isformed with an annular ridge on the side thereof adjacent said brushsocket members, said ridge being positioned to extend into the cut-awayspaces of said cut-away ends.

4. A rotary abrasive tool as claimed in claim 1, wherein the head of theclamping member is formed with an annular recess positioned to receive apart of the free end of the spool projecting through the adjustable endplate when said clamping member is in the clamping position.

References Cited in the file of this patent UNITED STATES PATENTS2,125,460 Plengemeier Aug. 2, 1938 2,194,577 Vonnegut Mar. 26, 19402,430,099 Bradley Nov. 4, 1947 2,474,063 Newton June 21, 1949 2,522,920Baltes Sept. 19, 1950 2,533,619 Pokras Dec. 12, 1950 2,600,613 Brunneret al. June 17, 1952 2,601,499 Bruner June 24, 1952

